Process for refining unwashed raw cane sugar



United States Patent 3,290,173 PROCESS FOR REFHNING UNWASHED RAW CANE SUGAR Santino Paul Marine, Tarrytown, N.Y., assignor to Corn Products Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Feb. 3, 1964, Ser. No. 342,294 14 Claims. (Cl. 127-63) The present invention relates to a process for refining raw cane sugar. More particularly, the present invention relates to a process, including electrodialysis, for refining raw cane sugar.

3,290,173 Patented Dec. 6, 1966 electrodialysis, and (5) treating the sugar solution to in- Commercial raw cane sugar refiners usually wash the raw sugar crystals by a first step called affination. This step consists of removing the adhering film of molasses from the surface of the raw sugar crystal. The separation is accomplished by co-mingling the raw sugar with a heavy sugar syrup 6570 Brix) and then purging the mixture in a centrifuge, followed by washing with water after the syrup has been spun off. This step dissolves the film of molasses but also a part of the sucrose, resulting in a removal of 944% of the initial raw sugar weight. The syrup spun off from the centrifuge and the washings makes up the afiination syrup. It contains most of the molasses, some of the ash, sucrose, invert sugars, and organic nonsugar substances originally present in the raw sugar.

The aflination syrup is put through various purification steps to recover as much of the sugar as possible. Gen erally, the affination syrup is treated with a defecation and filtration step to clarify the syrup. After clarification, the syrup is partially decolorized, followed by concentration to crystallize out the sugar. The remaining mother liquor is concentrated by vacuum evaporation of the water to crystallize out a second crop of crystals. The process of crystallization is repeated until as much sugar as possible has been recovered. The remaining syrup, after the last crystallization, is known as blackstrap molasses. The molasses solids constitute about 3-4% of the original raw sugar weight. The sugar crystallized from the afiination syrup is usually low grade and is known as a soft or light brown sugar. When used as a liquid sugar, it may be known as amber syrup. Some refiners reprocess the crystallized sugar through the entire refining process to produce a high grade refined liquid sugar or crystalline sugar.

It is an object of the present invention to provide a process for refining sugar in which substantially 100% of the sucrose values are recovered as a refined substantially pure white crystalline sugar.

It is another object of this invention to provide a process for refining raw cane sugar in which no affination syrup or blackstrap molasses is obtained.

It is another object of this invention to provide a process for refining raw cane sugar wherein crystalline substantially pure white sucrose is obtained in large yields.

It is another object of this invention to provide a process for refining raw cane sugar in which a substantially pure colorless sucrose liquid sugar is obtained.

It is another object of this invention to provide a process for refining raw cane sugar and producing a high grade substantially pure refined liquid invert sugar.

Other objects of the present invention will be apparent from the following description.

The present invention is especially suitable for refining raw cane sugar, wherein the affination step is eliminated, by (1) forming a raw cane sugar aqueous solution having a Brix between about 130 and about 65, (2) treating the raw cane sugar aqueous solution to substantially remove organic non-sugar substances or organic non-sugar substances and invert sugar, (3) decolorizing the sugar vert the sucrose.

In a specific embodiment of the present invention, raw cane sugar is dissolved in water to form a solution having a Brix between about 30 and about 65, preferably between about 45 and about 65. The resulting solution is treated with lime in an amount between about 0.5

and about 3.5% by weight on a sugar solids basis (thus effecting the substantial removal of invert sugar). After a holding period, the sugar solution is neutralized to a pH between about -6.0 and about 7.0 preferably between 6.5 and 6.8 with phosphoric acid. The neutralized solution is filtered. The sugar solution is next decolorized with a granular carbon to a color of less than 1.0 based on the Home scale, which will be described hereinafter. After decolorization, the ash of the decolorized sugar solution is reduced to less than 0.1% by electrodialysis. If desired, following the electrodialysis the demineralized sugar solution is treated with cation and anion exchange resins to further reduce the ash content to less than 0.009% based on a sugar solids basis, and to reduce the color to less than 0.2 based on the Home scale. The resulting sugar solution has a Brix in excess of 30, a pH approximating 6.5, is water white in color, contains less than 0.3% invert sugar, and contains less than 0.009% ash.

Raw cane sugar generally has a polarization of 96- 98. The polarization represents the amount of sucrose in a specific weight of raw sugar. For example, 100 grams of raw sugar having a polarization of 96" will have% grams of sucrose. The remaining 4 grams will consist of water, ash, invert sugar, and organic non-sugars.

The raw cane sugars may vary from season to season, from one geographical source to another and from shipment to shipment. Thus the sucrose content may vary from 96-98%, the invert sugar content from 0.5-1.5%, the ash content from 03-10%, the organic non-sugar substances content from 05-20%, and the water content from O.3l.0%. As the polarization of the sucrose increases, the total impurity content (ash, non-sugars, water, and invert sugar) decreases. However, one or more of the individual impurities may-not be decreased.

According to present commercial processes for refining raw cane sugar, it is estimated that 10% of the initial raw sugar weight is dissolved in the afiination step. 100 grams of raw sugar with a polarization of 96 will result in the following approximate quantitative sugar product:

Grams Washed raw sugar Low grade crystalline sugar or amber syrup (solids) 6.5

Blackstrap molasses on a solids basis 3.5

Heretofore it has not been economically possible to refine naw cane sugar without first producing an affination syrup. It is now possible by use of the combined steps of the present invention to refine raw cane sugar without producing an afiination syrup. The process of the present invention omits the afiination step, hence aflination syrup and blackstrap molasses are not produced. Asia result, the 944%. of the raw sugar lost into low grade sugar and blackstrap molasses by the usual'refining process, can be refined into high grade refined sugars by the new process. The omission of the affination step results in a considerable reduction of the cost of the production of the high grade refined sugars. ess of the present invention is more direct, simpler, and consists of fewer process steps than the usual refining process.

There are basically three desirable commercial sugar products which may be obtained by the present process as discussed below:

I. REFINED LIQUID SUCROSE The process consists of the following steps:

(1) Dissolution of the raw cane sugar.

(2) Defaction (lime is used under certain conditions to remove most of the invert sugar followed by neutralization with phosphoric acid; the solution is clarified by one or more of the methods of filtration, centrifugation, settling or flotation).

(3) Decolonization by the use of granular carbon.

(4) Demineralization by electrodialysis.

(5) Ion exchange (mixed cation and anion resins).

(6) Concentration to the desired degree.

'II. REFINED CRYSTALLINE SUCROSE The steps one through .four of the process for refining raw cane sugar, are also used in the refining process for making crystalline cane sugar. After step number 4 (demineralization by electrodialysis), the sugar syrup is evaporated (under vacuum) to a degree of supersaturation, and seeded to initiate crystallization of the sucrose. The crystallized sucrose is separated by centrifugation, washed, and dried in the usual crystalline refining metlhod.

III. REFINE-D LIQUID INV'ERT SUGAR Liquid invert sugar containing 4856% invert sugar and 44-52% sucrose, on solids basis, or liquid invert sugar containing 95-99.9% invert sugar and 0.15% sucrose, on solids basis, is refined from raw cane sugar by the following process steps:

(1) Dissolution of the raw cane sugar.

(2) Defecation (using phosphoric acid and neutralizing with lime so as not to destroy the invert sugar. The solution is clarified by one or more of the methods of filtration, centrirugation, settling, or flotation).

(3) Decolorization by the use of granular carbon.

(4) Demineralization by electrodial'ysis.

(5) Ion exchange. Cation resin only to reduce the pH and to remove cations.

(6) Inversion of sucrose. The solution is held at elevated temperature until a desired amount of invert sugar has been obtained.

(7) Ion exchange. Anionic exchange resin only to neutralize the sugar solution and to remove anions and color.

(8) Concentration.

All color determinations are based on the Home scale, wherein a dilute caramel solution is prepared of such concentration that when examined in a colorless glass water sample bottle, 3.34 cm. by 3.34 cm. by 11.43 cm., it matches the color of the standard glass when viewed against a similar bottle filled with distilled Water. The standard glass 'has a reading of 10 and has been reproduced by a special amber glass. Standards are prepared trom the caramel solution by dilution with distilled water to give readings from as high as 5.0 to as low as 0.1. The sample of liquid sugar is placed in the same sized bottle as the standards and comparison is made by transmitted light.

In order to have a fuller understanding of the present invent-ion, the process steps outlined above will now be discussed in detail.

In the production of refined liquid sucrose EErorn raw cane sugar commercial specifications require that the final product must contain less than 0.3% invert sugar,

The proc- 4 less than 0.009% ash, less than 0.2 color based on the Home scale, a pH between 6.5 and 7.2, and a concentration between 668 and 67.4 Brix.

When dissolving the raw cane sugar for step 1 of the refining process, the concentration of the solution may be between about 30 and about 65, preferably between 45 and 65 Brix. The desired concentration may depend upon the method of clarification. For example, if filtration or centrifugation or both is to be used for clarification, the preferred raw cane sugar concentration is between 30 and 50 Brix. If settling or flotation is to be used for clarification, the preferred concentration is between 50 and 65 Brix.

For example, for the preparation of a 45 Brix raw cane sugar solution, 9.9 kg. of raw cane sugar are added to 11.4 liters of water while agitating. The solution is heated to between about 50 and C. and agitated until all the sugar has dissolved. For other concentrations correspondingly increasing or decreasing amounts of raw sugar are used.

As previously mentioned, the invert sugar content of raw cane sugar varies from 0.5% to 1.5%. In order to meet specifications, it is necessary to reduce the invert sugar content to less than 0.3%. This is accomplished by the action of lime at increased temperature for a defined period of time. The concentration of lime, temperature, and the time required to reduce the invert sugar content are related. As the lime concentration is in creased, with temperature remaining constant, the time for reducing the invert sugar content to less than 0.3% is decreased. As the temperature is increased, with the lime concentration remaining constant, the time for reducing the invert content is also decreased. However, high temperature may result in undesirable increase in color. It has been found that a temperature of about C. resulted in optimal invert reduction at all levels of lime concentration without objectionable increase in color. Increasing the lime concentration and using a temperature of about 85 C. not only reduced the invert sugar content to less than 0.3% and decreased time requirement, but also effected an increase in color removal. Table I demonstrates the relationship between lime concentration, color, and time for the reduction of the invert sugar content to less than 0.3% at a temperature of about 85 C.

TAB LE I Percent Time, Percent Color Lime min. verb The lime concentration is on sugar solids basis. The color is based on the Home scale. After each time period for each level of lime concentration, the solution was neutralized with phosphoric acid to a pH between about 6.0 and 7.0, preferably between 6.5 and 6.8 and filtered to effect removal of organic non-sugar substances. The invert sugar and color values were determined on the filtrates. It is readily seen from the data above that with increasing lime concentration there is a progressive reduction of invert sugar content, a decrease in the time required for the reduction of the invert content, and an increasing amount of color removal.

The clarified cane sugar solution is decolorized to a color of less than 1.0 Horne scale by the use of granular carbon. The sugar solution should be maintained at a temperature less than 85 C. and it should remain in contact with the carbon for about 4 hours. Carbon may be used in amounts up to 10% of the sugar solids to be decolorized. The amount used will depend on the amount of color in the clarified sugar solution. Bone char or powdered vegetable carbon may also be used to decolorize the clarified sugar solution. Either of these carbons may be used in addition to granular carbon. Regardless of which carbon or combination of carbons is used, the color must be reduced to less than 1.0 Horne scale reading at this point in the process.

The ash of the decolorized sugar solution at a temperature between about 50 and 60 C. is reduced to less than 0.1% on a solid sugar basis by electrodialysis. The method involves the use of ion exchange membranes which are composed of a fabric backing impregnated with ion exchange resins. These may be 00635-0127 cm. thick, and are of two types, cation and anion. The cation exchange membranes are permeable only to cations and the anion exchange membranes are permeable only to anions. These membranes are arranged in a stack made up of pairs of membranes of alternating permeability between two electrodes. The membranes are separated by spacers which serve as gaskets and direct the flow of liquid between the membranes.

In order to effect demineralization by electrodialysis, the sugar solution containing dissolved salts (ionized cations and anions) is passed through the chamber having a cation exchange membrane on one side and an anion exchange membrane on the other, while water as a dilute electrolyte (0.02 N NaCl) is passed through chambers on each side of the chamber containing the sugar solution. This system is repeated in multiples throughout the stack. An is applied through the electrodes and this driving force causes cations to move through the cation exchange membranes and anions to move through the anion exchange membranes. Since cations cannot pass through the anion exchange membrane, and anions cannot pass through the cation exchange membrane, the cations and anions having passed into the water stream cannot continue into the next chamber containing the sugar solution, but are trapped and removed by water as wastes.

Decolorized sugar solutions with sugar concentrations ranging from 30 to 65 Brix, and containing from 0.3 to 1.5% ash (sugar solids basis) have been successfully demineralized by electrodialysis to an ash content of less than 0.1%.

In the demineralization of decolorized sugar solutions by electrodialysis, there is a consistent polarization at the anion exchange membrane, resulting in a marked decrease of the pH of the sugar solutions resulting in undesirable inversion of sucrose. This polarization is a result of the fact that the sugar solution, immediately adjacent to the anion exchange membrane, is devoid of ions necessary to carry the current, consequently the water of the sugar solution undergoes electrolysis. The hydroxyl ion of the water passes through the anion exchange membrane leaving a residual hydrogen ion. Concentration of the hydrogen ions increases as indicated by the persistent drop in pH with time. This polarization, resulting in a decrease of the pH of the sugar solution, occurs even when a very low current density, far below the determined polarization current density, is used.

The ditliculty of the drop of pH of the sugar solution and resulting inversion of the sucrose is overcome by controlling and maintaining the pH of the sugar solution between 6 and 7, preferably between 6.5 and 6.8 by the addition of small amounts of a solution of sodium hydroxide during the demineralization.

The electrodialyzed sugar solution at a temperature between about 48 and 52 C. from the preceding step is put through cation and anion exchange resins to reduce the ash content to less than 0.009% (sugar solids basis) and to reduce the color to less than 0.2 Home scale. The cation and anion exchange resins are preferably a mixed ion exchange resin consisting of a homogeneous 1:1 mixture of a carboxylic acid-tape cation exchange resin and a quaternary amine-type anion exchange resin. The carboxylic acid-type cation exchange resin is used in order to prevent inversion of sucrose.

If for some reason, after the ion exchange treatment,

the color is above 0.2, or if turbidity is present, the sugar solution may be treated with 0.2 to 0.3% powdered vegetable carbon and filtered,

The clear solution from the preceding step is concentrated under vacuum to the desirable sucrose concentration. In order to meet commercial standards, this concentration lies between 668 and 67.4 Brix.

In the process for the production of high grade refined crystalline sucrose, containing less than 0.05% invert sugar, less than 0.3 color and less than 0.015% ash, the first four steps of the preceding process are used. The clear sugar solution from the demineralization by electrodialysis step is evaporated under vacuum at a temperature between about 35 C. and about 85 C. until a supersaturated concentration is obtained (above 75 Brix). When this condition has been obtained, the sugar solution is seeded with very fine crystalline refined sucrose. Crystallization is allowed to take place and the crystals allowed to grow to the proper size. The crystals of the mother liquor are then transferred to a basket centrifuge or other separation means from which the mother liquor is separated, The remaining crystals are washed one or more times with water. The mother liquor and the washings are evaporated to a supersaturated sugar concentration and recycled to the crystallization step. The evaporation, crystallization, crystal growth, crystal separation, and crystal washing with water are repeated until as "much sucrose as possible is recovered from the sucrose solution. The sucrose crystals are collected, mixed, and air dried.

The process for the production of the high grade refined liquid invert sugar containing between 48 and 56% invert sugar, on solids basis, and between 44 and 52% sucrose, on solids basis, differs slightly from the two processes set forth above, since it is not necessary to remove the invert sugar already present. The final refined liquid invert sugar will have an ash content less than 0.009%, a color reading less than 0.30 on a Horne scale basis, a pH between 5.0 and 5.6 and a sugar concentration between 76.0 and 76.6 Brix.

The raw cane sugar is dissolved with water to form a solution having a B-rix between about 30 and about 65", preferably between about 45 and 65". At a temperature between 50 and C. the resulting solution is then clarified by the addition of phosphoric acid to the raw cane sugar solution. The quantity of phosphoric acid should be sufiicient to contain 0.1 to 0.15% P 0 on the basis of sugar solids. After mixing at a temperature of about C. for a few minutes, a suspension of lime is added to neutralize the raw cane sugar to a pH of 7.0 to 8.0, preferably between 7.2 and 7.6, the resulting suspension is filtered thereby clarifying the raw cane sugar solution and effecting the removal of organic nonsugar substances.

The resulting clarified solution is then decolorized with granular carbon in accordance with the preceding de colorization step discussed above.

The resulting decolorized solution is subjected to demineralization by electrodialysis. The electrodialysis process. is essentially the same as that described in the preceding process. However, the polarization which occurs in both the liquid sucrose process and the crystalline sucrose process, also occurs. in the electrodialysis demineralization of the sugar for the liquid invert sugar product. However, the decrease in pH of the sugar solution due to the polarization, results in some inversion of the sucrose which rather than being a disadvantage, in this case is an advantage since the final liquid invert sugar must contain about 50% invert sugar. Thus the maintenance of the pH between 6 and 7 with a solution of sodium hydroxide, as in the previous process, is not necessary in this process.

The resulting demineralized solution is put through a strong sulphonic acid-type cation resin. Practically all the cations are removed and the pH is reduced to about 3.0 and the temperature maintained at about 85 C. for approximately 30 minutes. After this period of time there is approximately 50% invert sugar. For the pro duction of a refined liquid invert sugar containing between 95 and 99.9% invert sugar, on solids basis, and between 0.1% and sucrose, on solids basis, the holding time required for the specified sugar solution described above is about one hour. However, it should be pointed out the holding time i not rigid. Variations in temperature, Brix, concentrations and pH of the cation resin treated solution will result in variation of the rate of sucrose inversion and thus the amount of invert sugar produced in a given time.

For the liquid invert sugar containing 4856% invert sugar and 44-52% sucrose, the color should be reduced to less than 0.30 on a Home scale basis. The ash should be less than 0.009% and the pH should be neutralized to a pH between 5 and 5.6, after the anion exchange treatment.

For the liquid invert sugar containing 9599.9% invert sugar and 0.1-5% sucrose, the color should be less than 0.6 on a Home scale basis. The ash should be less than 0.015% and the pH should be neutralized to between 5.0 and 5.6, after the anion exchange treatment.

Following the inversion step, the liquid invert sugar cooled to a temperature between about 48 and 52 C. is subjected to ion exchange treatment with an anion resin only, to neutralize the low pH inverted sugar solution and to remove the anions as well as to remove color.

The clear liquid invert sugar containing 4856% invert is concentrated under vacuum to a Brix between 76.0 and 76.6". The clear liquid invert sugar containing 9599.9% invert is concentrated under vacuum to a Brix between 71.7 and 72.3.

The following specific embodiments are included for purposes of exemplification only and in no way are intended to limit the scope of this invention.

Example I.Pr0ducti0n of refined liquid sucrose from raw cane sugar A 45 Brix raw cane sugar solution is formed by adding 9.9 kilograms of raw cane sugar to 11.4 liters of water while agitating. The solution is heated to between about 50 and 80 C. and agitated until all the sugar has dis- 8 75% phosphoric acid, about 0.5% filter aid is added, and the solution is filtered.

The clarified solution is decolorized by the use of 0.71 kilogram of granular carbon to a color of 0.7 (Horne scale). The carbon is poured into 4 columns (5.08 cm. inside diameter, 38.1 cm. long) each containing about 0.18 kilogram of carbon. The columns are connected in series and kept in a hot water bath. The clarified sugar solution at a temperature of about 70 C. is put through the columns, with a downward fiow, discharging from the fourth (last) column at a rate of 4 ml. per minute.

The clarified decolorized sugar solution at a temperature between and C. is passed through an electrodialyzer cell consisting of a 9" x 10", 20 cell pair electric membrane electrodialysis stack to reduce the ash content to less than 0.1% (sugar solids basis). The pH of the sugar solution is maintained between 6 and 7, preferably between 6.5 and 6.8 by the addition of about 40 ml. of a 10% sodium hydroxide solution (for each 10 liters of sugar solution treated) in incremental amounts during demineralization. Using the above conditions, the ash content is reduced to 0.026% (sugar solids basis) in one hour.

The electrodialyzed demineralized sugar solution from the previous step is put through a mixed cation and anion exchange resin bed to reduce the ash content to less than 0.009% (sugar solids basis) and the color to less than 0.2 (Home scale). A carboxylic type of cation exchange resin is used in order to prevent inversion.

The solution is brought to a temperature between about 48 and 52 C. and put through a column containing about 280 cc. of a homogeneous mixture of cation exchange resin and anion exchange resin in a ratio to each other of about 1:1.

The rate of flow through the column is maintained at 10 ml. per minute. The composite efiluent sugar solu tion has an ash content of 0.001% (sugar solids basis), a pH of 6.5 and a color less than 0.2 (Horne scale). The solution is concentrated under vacuum to a sucrose c0ncentration of about 67.4 Brix.

Example 11 A raw cane sugar having a high ash content is processed according to the steps in Example I to yield a high grade, refined liquid sucrose. The table below sets forth analytical data obtained after completion of each step. The data are based on sugar solids, and the color is based on the Home scale.

Brix pH Color Percent Percent Invert; Ash

Step #1, dissolution (Raw Sugar) 46. 5 6. 3 41 0. 57 0. 025 Step #2, detection with clarification; invert removal 43. 9 7. 2 43 0.09 0. 921 Step #3, deeolonzatlon with granular carbon 43. 3 6. 3 0. 7 0. 14 0. 922 Step #4, demincralization by electrodialysis 31.8 7. 0 0. 7 0. 10 0.051 Step #5, demineralization by mixed cation and anion exchange resins 31. 8 6. 5 0 19 0.001 Step #6, concentration, under vacuum 67. 4 6. 5 0 19 0.001

1 Water white.

solved. To this solution 99 grams of lime are added, and the solution heated to C. and held at that temperature for about an hour. While contining to maintain the temperature at 85 C., the solution is neutralized to a pH be tween 6.0 and 7.0, preferably between 6.5 and 6.8 with Example 111 A raw cane sugar, having a high invert sugar content is processed according to Example I to yield a high grade, refined liquid sucrose. The table below sets forth analyt ical data obtained after completion of each step.

Brix pH Color Percent Percent Invert Ash Step #1, dissolution (Raw Sugar) 45. 6 6. 1 42. 3 1. 32 0. 41 Step #2, defecation with clarification; invert removal 43. 4 6. 7 68. 1 0. 25 0. 66 Step #3, decolorization with granular carbon 40. 9 6. 9 1. 0 0. 26 0. 64 Step #4, demmeralization by electrodialysis 30. 7 6. 5 1.0 0.28 0.05 Step #5, demineralization by mixed cation and anion exchange resins 30. 7 6. 5 0. 15 0. 28 0.001 Step #6, concentration under vacuum 67. 4 6. 5 0.15 0. 29 0. 001

9 Example IV A raw cane sugar is refined by the first four steps of Example I and then crystallized into a high grade, refined crystalline sucrose.

10 product. However, the decrease in pH of the sugar solution, due to the polarization resulting in some inversion of the sucrose, is not a disadvantage, but rather an advantage. Since the final liquid invert sugar should contain at least about 50% invert sugar, the maintenance of the The clear sugar solution from step 4 of Example I is 5 evaporated under vacuum at a temperature between about betweer} and 7 Wlth glkah as m i production of o o a refined liquid or crystalline sucrose is not necessary. 35 and about 82 until a supersaturated sugar At the end of the dimineralization ste the H is about concentration is obtained (above 75 Brix). The con- 5 5 p gentrated solution is seeded with very fine crystalline re- The deminerauzed sugar Solution is Subjected to a nod sucrose and crystalllzation 1S allowed to take place. 10

strong sulfonic acid type cation exchange resin treatment. The crystals and mother liquor are transferred to a basket t f hi h th 0th u ut Substantially all of the cations are removed and the pH f n Om W e m er g {2 un is reduced to about 3.0. The composite efiluent sugar 6 Iemammg Crys are Wate? was 6 e mot er solution from the preceding step is adjusted to and mainliquor and water washings are either optionally concen- 15 mined at a temperature of for about minutes trated and the crystallizat on process repeated, or recycled Analysis indicates there is 51% invert Sugar (sugar solids 9 an appropnate Place 111 the e et example, the basis). The holding time at 85 c. for 30 minutes is 11111101 y be recycled to the cllstalllzatlon P- sufficient for the specific sugar solution described in the The sucrose crystals are air dried. first 5 steps for the production of a refined liquid invert The table below sets forth analytical data obtained 20 sugar containing 48-56% invert and between 44 and 52% after completion of each step: sucrose.

Brix pH Color Percent Percent Invert Ash Step #1, dissolution (Raw Sugar) 45.7 6.2 I 41.8 0.59 0.954 Step #2, detection with clarification; invert removal 44.2 6.3 36.0 0.09 0.949 Step #3,decolorization with granular carbon 42.6 6.1 0.7 0.16 0.955 Step #4, demineralization by electrodialysis 32. 2 7. 0 0. 5 0. 21 0.026 Step #5, crystallization and drying-crystalline, dry sucrose 6. 8 0.3 0.02 0. 003

Example V For theproduction of a refined liquid invert sugar con- This example illustrates the preparation of liquid invert g g'i 95 E 5 3 2 g g gfi sugar. The process is generally the same as that for mak- I an 0 P9 6 mg i req or ing refined liquid or crystalline sucrose, with the excep- 0110 Sugar so y one 3 w 1t 15 tions noted vantageous to make periodic analysis of the invert sugar so The concentration of the dissolved raw cane sugar may that a contrPl the p h h may be m?j1111tai 11edbe between about 30 and 65, preferably between 45 The holdlhg tlme used not g Vanatwns and 65 BriX. This step is the same as step 1 for makin 40 perature, Brix, concentration and pH of the cation exrefined liquid or crystalline sucrose. In step 2 (defeca change resin treated sugar solution will result in variation tion with clarification) the invert sugar is not removed. of the rate of sucrose inversion and thus the amount of In the process for the production of liquid invert sugar, invert sugar produced ina given time. it is not necessary to remove the invert sugar from the .The liquid invert sugar solution from step 6 is adjusted raw cane sugar. Therefore, phosphoric acid is added first t a temperature between about 48 and 52 C. and put e Y Cane Sugar SolutlOIlq l] p through a column containing an anion exchangeresin. phorrc acid added should be sufficient to conta n between The pH of the Composite emuent sugar Solution is P Z 9 on the basls of Sugar F- After This pH is adjusted to 5.2 with dilute hydrochloric acid. i f and Wlth h i i 5 2 2 i After the pH adjustment if there is turbidity in the sugar 6W a .Suspenslon 0 a 13 solution or the color of the invert sugar liquid solution added to neutralize the raw cane sugar to a pH between 1 is more than 0.30 for the 48%56% invert sugar and 7.0 and 8.0, preferably between 7.2 and 7.6. A filter 457-527 H ms 0 mo th 06 f th 99 97 aid is added and the raw cane sugar heated to about 85 0 0 s c e r an 6 0 is darified by filtration mvert sugar and 0.1%-5% sucrose, the sugar solution The decolorization With granular carbon (step 3) is should be treated with 0.2O.3% powdered vegetable carthe same as step 3 for making refined liquid or crystalline bon and Intel-Pd" sucrose. The clarified sugar solution is then subjected to The l l Invert sugar 18 Concentrated d r Va treatment by electrodialysis. The polarization Which oc- 111.1110 3 Bnx between 76-00 and curs as described in step 4 for making refined liquid or The table below Sets forth analytical data t n d crystalline sucrose also occurs in the electrodialysis deafter the completion of each step in the preparation of mineralization of the sugar for the liquid invert sugar 51.6% liquid invert sugar:

Brlx pH Color Percent Percent Invert Ash Step #1, dissolution (Raw Sugar) 42.7 I 5.8 67.5 1.09 0.646 Step #2, defecation with clarification 36.1 7. 4 32. 7 1. 21 0.541 Step #3,decolorization with granular carbon. 30.9 7.2 0.9 3.45 0.556 Step #4, demineralization by eleetrodialysis.. 30. 4 5. 5 0. 4 3. 49 0. 056 gzep eationremqval and pH reduction-.. 6 HIVQISlOIl O SUOIOSQ Ste g #7, anion and color removal, neutraliza- 4 7 13 O 003 101'1 Step #8, concentration (under vacuum) 76. 2 5. 2 0. 13 51.6 0. 007

The table below sets forth analytical data obtained after completion of each step in the preparation of 96.7% liquid invert sugar:

() decolorizing the treated sugar solution with granular carbon, and (6) passing the decolorized sugar solution through an Brix pH Color Percent Percent Invert Ash Step #1, dissolution (Raw Sugar) 45. 5 6. 0 67.7 0.9 0.336 Step #2, defecation with clarification 42. 7 7. 2 26. 1 1. 7 0. 267 Step #3, decolorization with granular carbon. 41. 7 7. 2 1.0 1. 7 0. 267 Step #4,demineralizationwith electrodialysis. 31.1 6.0 0.8 4.4 0. 028 it? if? iii rrfiil llficisl PH Step #7: anion and color reniiiiritiiii'za 4 27 7 002 sri fi ls;5550115555153zasau'aaaaaij113:: 71.8 5.5 0. 30 96.7 0.002

Although the invention has been described by reference electrodialyzer cell to yield a sugar solution having a to certain specific embodiments thereof, it is to be under- Brix above about 30, a color index of less than 1.0 stood that such matters are purely illustrative for the purbased on the Horne scale, a pH of about 6.5, and pose of clarifying the invention and the invention is in containing less than about 0.3% invert sugar and no sense to be considered limited thereto. Numerous less than about 0.1% ash. modifications and equivalents of the present invention 5. A process as in claim 4 wherein the refined sugar will be apparent from the foregoing description to those solution is subjected to further treatment with a mixed skilled in the art. ion exchange resin to reduce the ash content to less than I claim: about 0.009% and the color index to less than about 0.2

1. A process for refining unwashed raw cane sugar, based on the Home scale. wherein the affination step is eliminated, which comprises: 6. A process as in claim 4 wherein the refined sugar 1) dissolving unwashed raw cane sugar in water to solution is concentrated to a Brix of between about 668 provide an aqueous solution having a Brix between and about 67.4", about and about 65, 7. A process as in claim 4 wherein during electrodialy- (2) treating the raw cane sugar aqueous solution to sis the pH of the sugar solution is maintained between substantially remove the organic non-sugar sub- 30 about 6.0 and about 7.0 by the addition of incremental stances, amounts of sodium hydroxide.

(3) decolorizing the treated sugar solution, and 8. A process as in claim 4 wherein the suger solution (4) demineralizing the decolorized sugar solution by is subjected to further treatment by evaporation and conpassing said solution through an electrodialyzer centration to crystallize the sugar which is recovered as cell. a substantially pure, white, dry crystalline sugar having 2. A process for refining unwashed raw cane sugar, an ash content of 0.004%, a color of 0.3 on a Home wherein the afiination step is eliminated, which comscale basis, an invert sugar content of 0.02%, and a pH prises: of 6.8.

(1) dissolving unwashed raw cane sugar in water to 9. A process for preparing liquid invert sugar from yield an aqueous solution having a Brix between unwashed raw cane sugar, wherein the aflination step is about 30 and about 65, eliminated, by

(2) treating the raw cane sugar aqueous solution to (1) dissolving unwashed raw cane sugar in water to substantially remove invert sugar and organic nonform an aqueous solution having a Brix between sugar substances, about 30 and about 65,

(3) decolorizing the treated sugar solution, and (2) treating the raw cane sugar aqueous solution to (4) demineralizing the decolorized sugar solution by substantially remove the organic non-sugar subpassing said solution through an electrodialyzer stances, cell. (3) decolorizing the treated sugar solution,

3. A process for refining unwashed raw cane sugar, (4) demineralizing the decolorized sugar solution by wherein the afiination step is eliminated, which compassing the solution through an electrodialyzer cell, prises: and

(1) dissolving unwashed raw cane sugar in water to (5) treating the sugar solution to invert the sucrose. yield an aqueous solution having a Brix between 10. A process for preparing liquid invert sugar which about 30 and about 65, comprises:

(2) removing invert sugar and organic non-sugar sub- (1) dissolving raw cane sugar in water to form a solustances by treatment of the sugar solution with lime tion having a Brix between about 45 and about followed by neutralization with phosphoric acid,

(3) decolorizing the treated sugar solution by treat- (2) treating the sugar solution with phosphoric acid ment with granular carbon, and in an amount sufficient to contain between about (4) demineralizing the decolorized sugar solution by 60 0.10 and about 0.15% P 0 on the basis of sugar passing the solution through an electrodialyzer cell solids, to yield a refined sugar solution having a Brix above (3) neutralizing the sugar solution with lime to a pH about 30, a pH of about 6.5, and containing less between about 7.0 and about 8.0, than about 0.3% invert sugar and less thanv about (4) filtering the neutralized sugar solution,

0.1% ash. 5 (5 decolorizing the sugar solution with granular 4. A process for preparing refined liquid sucrose from carbon,

Unwashed raw 03116 8 which comprises! (6) passing the decolorized sugar solution through an (1) dissolving unwashed raw cane sugar in water to electrodialyzer cell,

form a solution having a Brix between about 45 (7) subjecting the electrodialysis-treated sugar solution and about to treatment with a strong sulfonic acid-type cation (2) treating the resulting sugar solution with between exchange resin whereby the pH is reduced to about about 0.5 and about 3.5% by weight of lime, 3,0,

.(3) neutralizing the sugar solution with phosphoric ('8) maintaining the temperature of the sugar solution acid to a pH between about 6.0 and about 7.0, at about 85 C. for a period of time suificient to (4) filtering the neutralized sugar solution, yield the desired amount of inversion, and

(9) adjusting the pH of the resultant liquid invert sugar to between about 5.0 and about 7.0.

11. A process for preparing liquid invert sugar from raw cane sugar wherein the affination step, is eliminated, which comprises:

(1) forming a raw cane sugar aqueous solution by dissolving raw cane sugar in water at a tempera-ture between about 50 C. and about 80 C. to form a solution having a Brix between about 45 and about 65,

(2) treating the sugar solution with phosphoric acid in an amount sufiicient to contain between about 0.1% and about 0.15% P on the basis of sugar solids,

(3) neutralizing the sugar solution with lime to a pH between about 7.0 and 8.0,

(4) heating the solution to about 85 C.,

(5) clarifying the solution by filtration,

(6) deoolorizing the sugar solution by treatment with up to granular carbon by weight to the weight of sugar solids at a temperature less than 85 C. with a contact time of 4 hours to a color on a Horne scale basis of less than 1.0,

(7) demineralizing to an ash content of less than 0.1% by passing the solution through an electrodialyzer cell at a temperature between about 50 and about 60 C.,

(8) subjecting the electrodialysis treated solution to treatment with a strong sulfonic acid-type cation exchange resin to reduce the pH to about 3.0,

14 (9) maintaining the resin treated solution at about C. for a period of time suflicient to yield 48% to 56% invert sugar, and

(10) treating the inverted sugar with an anion exchange resin to neutralize the sugar solution to a pH between about 5.0 and about 7.0.

12. A process as in claim 11 wherein the resin treated solution is maintained at about 85 C. for a period of time suflicient to yield between and 99.9% invert sugar.

13. A process as in claim 11 wherein the refined liquid invert sugar solution is concentrated to la Brix of between about 76.0 and about 766.

14. A process as in claim 12 wherein the refined liquid invert sugar solution is concentrated to a Brix of between about 71.7 and about 723.

References Cited by the Examiner UNITED STATES PATENTS 2,594,440 4/ 1952 Hughes et a1 127-41 2,688,572 9/1954 Warshaw l2754 2,860,091 11/1958 Rosenbeng 204-180 X 2,863,813 12/1958 Juda et a1 20418O X OTHER REFERENCES Spencer-Meade, Cane Sugar Handbook, eighth edition, 1945, pp. 263-265, 287-289, 294-297, 308 and 323-327 and 333, John Wiley and Sons, New York.

MORRIS O. WOLK, Primary Examiner.

MICHAEL E. ROGERS, Examiner. 

1. A PROCESS FOR REFINING UNWASHED RAW CANE SUGAR WHEREIN THE AFFINATION STEP IS ELIMINATED, WHICH COMPRISES: (1) DISSOLVING UNWASHED RAW CANE SUGAR IN WATER TO PROVIDE AN AQUEOUS SOLUTION HAVING A BRIX BETWEEN ABOUT 30* AND ABOUT 65*, (2) TREATING THE RAW CANE SUGAR AQUEOUS SOLUTION TO SUBSTANTIALLY REMOVE THE ORGANIC NON-SUGAR SUBSTANCES, (3) DECOLORIZINNG THE TREATED SUGAR SOLUTION, AND (4) DEMINERALIZING THE DECOLORIZED SUGAR SOLUTION BY PASSING SAID SOLUTION THROUGH AN ELECTRODIALYZER CELL. 